Apparatus and method for generating plasma

ABSTRACT

An apparatus comprising a semiconductor processing chamber, a plasma generator, and a pipe connecting a semiconductor processing chamber and the plasma generator. The plasma generator includes a generation chamber, a radio frequency generator which generates an ion plasma within the generation chamber, and a magnetic device which confines the plasma primarily within a center region of the generation chamber.

BACKGROUND TO THE INVENTION

1). Field of the Invention

The present invention relates generally to cleaning of semiconductorprocessing chambers and auxiliary equipment such as interconnectingpipes and, more specifically, to an apparatus and a method wherein anion plasma is generated externally of a semiconductor processing chamberand the ion plasma is then introduced into the semiconductor processingfor cleaning purposes.

2). Discussion of Related Art

Semiconductor chips are manufactured by processing a wafer in respectivesemiconductor processing chambers. Such processing may include chemicalvapor deposition (CVD), physical vapor deposition (PVD), or any otherprocessing which is known in the art. The processing chamber used foreach process is designed for purposes of carrying out the respectiveprocess. Chemical vapor deposition, for example, includes the process ofdistributing a chemical gas within a processing chamber to produce afilm on a wafer substrate. The deposition film is also deposited on thesurfaces of other components within the processing chamber. Byproductsthat are produced during the film deposition process are also depositedon the various components within the chamber, including the chamberwalls. As a result, the deposition films and byproducts deposited ontothe various processing chamber components must be clean out from time totime.

SUMMARY OF THE INVENTION

In one embodiment of the present invention, a system is providedcomprising a semiconductor processing chamber and a plasma generationchamber, located externally of the semiconductor processing chamber, inwhich reactive ions are generated for purposes of cleaning thesemiconductor processing chamber. A radio frequency generator isprovided for dissociating a gas, when contained within the plasmageneration chamber, into reactive ions. A magnetic device is alsoprovided for creating a magnetic field which acts to confine the ions toa central region within the generation chamber, away from the chamberwalls. A conduit permits the flow of ions from the generation chamber tothe processing chamber.

The invention also provides a method of cleaning a semiconductorprocessing chamber wherein a gas is dissociated into reactive ions, theions are magnetically confined, and the ions are then introduced intothe semiconductor processing chamber.

The invention further provides a method of generating a plasma,comprising the steps of dissociating a gas into reactive ions, andmagnetically confining the ions. The ions are preferably magneticallyconfined while they are being formed.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further described by way of example with reference tothe accompanying drawings wherein:

FIG. 1 is a partially sectioned side view illustrating a systemaccording to the invention;

FIG. 2 is a partially sectioned perspective view of a plasma generatorfor use in the system of FIG. 1;

FIG. 3 is an end view of a portion of the plasma generator of FIG. 2;

FIG. 4 illustrates a particle with an electric charge which is movinginto a magnetic field;

FIG. 5 shows four magnets facing one another and a particle with anelectric charge located in an area between the magnets;

FIG. 6 is an end view of an electric coil which is connected to analternating current source;

FIG. 7 is a side view of the coil of FIG. 6;

FIG. 8 is a perspective view of a plasma generator in another embodimentof the present invention;

FIG. 9 is a top view of the plasma generator of FIG. 8 with the magneticdevice removed in order to expose the RF coils;

FIG. 10 is a partial cross-sectional top view of the plasma generatorshown in FIG. 9;

FIG. 11 is a cross-sectional side view of the gas inlet adapter shown inFIG. 10; and

FIG. 12 is a cross-sectional side view of the cooling medium inletmanifold shown in FIG. 10.

DESCRIPTION OF PREFERRED EMBODIMENT

In the following description, for purposes of explanation, numerousdetails are set forth in order to provide a thorough understanding ofthe present invention. However, it will be apparent to one skilled inthe art that these specific details are not required in order topractice the present invention. Certain specifics regarding apparatus,materials, dimensions, process parameters and results are recited. Theseand other specifics are recited in order to provide an example of aworkable embodiment of the invention, and may be altered according topreference or requirement without departing from the broader scope ofthe invention.

The following description relates to an apparatus and a method ofcleaning a semiconductor processing chamber. A gas is introduced into aplasma generation chamber and vibrated at radio frequency. Vibration ofthe gas causes disassociation of the gas into reactive ions. The ionsthen flow out of the generation chamber through a pipe and into asemiconductor processing chamber. The gas is then allowed to clean thesemiconductor processing chamber by reacting with contaminants therein.

FIG. 1 of the accompanying drawings illustrates a system 110 accordingto one embodiment of the present invention. The system 110 includes aplasma generator 112, a semiconductor processing chamber 114, a pipe 116connecting the plasma generator 112 and the semiconductor processingchamber 114 with a shower head portion 118 of the pipe 116 extendinginto the semiconductor processing chamber 114, and a pump 120 with a lowpressure side 122 connected to the semiconductor process chamber 114.

The semiconductor processing chamber 114 usually contains a susceptor115 and may be a chemical deposition chamber, a physical depositionchamber, a high density plasma deposition chamber, a reactive etchchamber, or any other semiconductor processing chamber which is known inthe art, regardless of the purpose that it serves. In the embodimentdescribed, the plasma generator 112 generates fluorine ions which areintroduced into the semiconductor processing chamber 114 through thepipe 116 for purposes of cleaning the semiconductor processing chamber114. The walls of the semiconductor processing chamber 114 and any othercomponents located within the semiconductor processing chamber 114 willtherefore be made of materials which can be cleaned with fluorine ionswithout undue damage thereto. A material which can be cleaned withfluorine ions is aluminum.

The pipe 116 is made of aluminum and is formed with a number of openings124 in the shower head portion 118. The openings 124 are spaced from oneanother so as to be spread out over the width of the semiconductorprocessing chamber 114. In one embodiment, the fluorine ions areintroduced into the processing chamber through the process gasdistribution ring.

FIG. 2 is a perspective view of the plasma generator 112 of FIG. 1. Theplasma generator 112 includes a housing 130 and respectively a tubulargeneration chamber 132, a radio frequency generator 134 and a magneticdevice 136 mounted within the housing 130. The radio frequency generator134 is used to generate a reactive ion plasma within the generationchamber 132 and the magnetic device 136 is used to control the reactiveion plasma within the generation chamber 132.

The housing 130 is typically made of aluminum for low magnetizationreasons and is connected to ground 138. Although only a section of thehousing 130 is shown, it should be understood that the housing surroundsthe generation chamber 132, the radio frequency generator 134 and themagnetic device 136.

The generation chamber 132 extends along the length of the housing 130with rings 140 supporting the generation chamber 132 within opposingwalls of the housing 130. A gas inlet 142 is provided at one end of thegeneration chamber 132 and an opposing end of the generation chamber 132is open with a much larger ion outlet 144. The generation chamber 132 istypically made of sapphire and has an inner diameter of about 25 mm, awall thickness of about 1.6 mm, and a length of about 250 mm. Thedimensions of the generation chamber 132 are not important for purposesof the invention and are given merely for purposes of providing anexample of a workable embodiment of the invention.

The radio frequency generator 134 includes a bracket 150, a connector152, a radio frequency source 154, and a coil 156. Coil 156 is generallyof a tubular construction and is typically made of copper with anexternal silver plating.

The bracket 150 and the connector 152 are located on opposing sides of awall (not shown) of the housing 130 and a electrically conductive link158 connects the bracket to the connector 152. The radio frequencysource 154 is connected to the connector so that alternating currentwithin the radio frequency range is supplied to the bracket 150.

The coil 156 spirals around the generation chamber 132, and has a firstend 160 which is secured to the bracket 150. A second end 162 of thecoil 156 is mounted to a wall of the housing 130 by means of a bracket164. The second end 162 is thus connected to the ground 138 via thehousing 130. The brackets 150 and 164 support the coil 156 substantiallyconcentrically around the generation chamber 132. Alternating currentcan thus be supplied to the coil 156 by operation of the radio frequencysource 154. The coil 156 typically has about five to ten turns. It isappreciated, however, that the invention is not limited to any specificnumber of coil turns. The number of turns will generally increase withthe dimensions of the generation chamber 132 in order to ensuresufficient coverage around the generation chamber 132.

Capacitors 166 bridge the bracket 150 and a wall of the housing 130. Thecapacitors 166 are selected to match the frequency supplied by the radiofrequency source with the conductance characteristics of the coil 156 sothat the alternating power delivered to the coil 156 is tuned foroptimal reasons.

A water inlet connector 168 and a water outlet connector 170 extendthrough a wall of the housing 130. A flexible pipe 172 connects thewater inlet connector 168 to the first end 160 of the coil 156. Water174 can thus be introduced into the water inlet connector 168 which thenflows through the flexible pipe 172 into the first end 160, whereafterthe water flows through the coil and out of the water outlet connector170. The temperature of the coil 156 can so be controlled.

It should be noted that electric power, in the form of the radiofrequency source 154, and a supply of water are both connected to thefirst end 160, which could be hazardous. The electrically non-conductiveflexible pipe 172 is, however, sufficiently long so as to increase theresistance of the water 174 flowing therethrough. The water 174 enteringthrough the water inlet connector 168 is thus safe and power loss to thewater is minimized. The majority of the flexible pipe 172 is a roll 176lying on a floor of the housing 130. The second end 162 of the coil 156is grounded by means of the bracket 164, thus making safe the waterleaving the coil 156.

The magnetic device 136 is in the form of tubular member 180 locatedaround the coil 156. (See FIG. 3.) The tubular member 180 includes fourpermanent magnets 182 which extend along the length thereof. The magnets182 oppose one another with the generation chamber 132 located betweenthe magnets 182. The magnets create a magnetic field of between 200 and4000 Gauss, typically less than 2000 Gauss. The magnetic field createdby the magnets may be adjusted to meet the performance requirements of aparticular application.

FIG. 4 is a representation of a particle with an electric charge q whichmoves into a magnetic field. The magnetic field has a magnetic fluxdensity B and the particle moves with a velocity u. A force f is createdon the particle according to the vector notation:

    f=qu×B.

The force f is in a direction which is normal to a plane containing uand B. The force f thus causes deflection of the particle so that theparticle is prevented from moving through the magnetic field.

FIG. 5 represents a magnetic field 14 that is produced by the magnets182 of magnetic device 136. The magnets 182 are used for confining aparticle with an electric charge q. Opposing magnets 182a and 182c arepolarized with north facing one another and opposing magnets 182b and182d are polarized with south facing one another. A magnetic field 14runs through an area 16 between the magnets 182 and from one magnet toan adjacent magnet. The particle with an electric charge q is locatedwithin the area 16. Movement of the particle into the magnetic fieldresults in a force acting upon the particle which deflects the particleas hereinbefore described. Continuous deflection of the particle resultsin the particle being confined primarily within a center region of thearea 16. The center region of the area 16 typically corresponds to thecenter region of the generation chamber 132.

FIGS. 6 and 7 are end and side views of an electric coil 156 which isconnected to a radio frequency source 154, such as an alternatingcurrent source.

An electromagnetic field is created by the electric coil 156. Theelectromagnetic field comprises an alternating electric field 22 and analternating magnetic field 24. The alternating electric field 22 iscreated within the coil 156 when the alternating current source isoperated. The electric field 22 is circular with a center pointcorresponding to the center of the coil 156.

The alternating magnetic field 24 is also created within the coil 156when the alternating current source is operated. The magnetic field 24forms along the length of the coil 156. The magnetic field 24 issubstantially perpendicular to the magnetic field 14 and there is littleor no interaction between the magnetic fields 14 and 24.

The electric field 22 and the magnetic field 24 may be utilized foractuating gas particles so that the gas particles are dissociated intoionized particles. The gas particles are dissociated by vibration in thedirections of both the electric field 22 and the magnetic field 24. Theelectric field 22 and the magnetic field 24 acting in unison causes thegas particles to spin, which results in dissociation of the gasparticles into ionized particles. Any dissociation is, of course,dependent on the current and frequency provided by alternating currentsource 154.

It should be noted that the gas particles and the ionized particles areactivated in the directions of the electric field 22 and the magneticfield 24 only. There is thus no component of movement of the gasparticles or the ionized particles in a direction away from the centeraxis toward the coil 156. Possible damage to the coil due to contact bythe gas particles or ionized particles is therefore prevented.

FIG. 3 is an end view of the components shown in FIG. 2, and shows thegeneration chamber 132, the coil 156 around the generation chamber 132,and the tubular member 180, including the magnets 182, around the coil156.

In use, the radio frequency source 154 is operated so as to create afrequency within the radio frequency range of between about 300 kHz and300 MHz. Such a frequency may be about 13.56 MHz, about 2 MHz, orbetween 350 kHz and 500 kHz. Electric power of between 100 W and 2 kW issupplied to the radio frequency source 154. An alternating currentwithin the radio frequency range is thus created within the coil 156. Analternating electric field and an alternating magnetic field are alsocreated as hereinbefore described with reference to FIGS. 6 and 7.

A gas, such as NF₃, is then introduced through the gas inlet 142 intothe generation chamber 132. The gas is then dissociated into a reactiveion plasma containing nitrogen and fluorine ions, as also hereinbeforedescribed with reference to FIGS. 6 and 7. The fluorine ions are veryreactive and may cause damage to the generation chamber 132 should theycome into contact with the generation chamber 132. The magnets 182 arearranged as previously described with reference to FIG. 2 so that theyconfine the fluorine ions primarily in a center region of the generationchamber 132. The fluorine ions are thus continuously deflected away froman inner wall of the generation chamber 132. Damage to the generationchamber by the ions is thereby prevented and reduction in wallbombardment minimizes cooling requirements of the chamber 132.

The NF₃ molecules are dissociated by spinning caused by the electricalfield and the magnetic field generated by the coil 156, as previouslydescribed. The magnetic field created by the magnets 182 assists infurther spinning the NF₃ ions so that the NF₃ molecules are dissociatedat a faster rate and more effectively than with the coil 156 alone.

The electric field vibrates the molecules in a circular path with acenter point corresponding to the center of the generation chamber 132and the magnetic field vibrates the NF₃ molecules in a direction whichis along the length of the generation chamber 132 so that movement ofthe NF₃ molecules, or the fluorine ions, is not in a direction which istowards an inner wall of the generation chamber 132. The forces actingon the molecules are therefore not in a direction which would causedamage to the generation chamber 132.

Once the fluorine ions are formed, they flow from the generation chamber132 through the ion outlet 144. The ion outlet 144 is much larger thanthe gas inlet 142 so as not to unnecessarily restrict the flow of thereactive fluorine ions.

It should be noted that the fluorine ions are magnetically confinedwhile they are being formed. It should also be noted that the NF₃ gas isdissociated while the fluorine ions are magnetically confined within thegeneration chamber 132, while the gas flows into the generation chamberthrough the gas inlet 142, and while the ions are flowing out of thegeneration chamber 132 through the ion outlet 144.

The fluorine ion plasma then flows through the pipe 116 to the showerhead portion 118 from where it is sprayed into the semiconductorprocessing chamber 114 through the openings 124. The pipe 116 and theshower head portion 118, being made of aluminum, are relativelyresistant to attack by the fluoride ions so that minimal damage iscaused to the pipe 116 or the shower head portion 118 when the fluorineions flow therethrough. Introduction of the fluorine ion plasma into asemiconductor processing chamber 114 causes the fluorine ions to reactwith contaminants such as oxides, deposition byproducts, acidicparticles or other contaminants within the semiconductor processingchamber 114. Any products resulting from the reaction are then pumpedout of the semiconductor processing chamber 114 by means of the pump120.

A higher plasma density can be created by generating the plasma undercontrolled conditions within a specifically designed plasma generationsystem, when compared to generating a similar plasma within asemiconductor processing chamber 114 utilizing the same techniques. Afluorine ion plasma density of about 10¹⁴ /cm³ can generally be createdwhen a 2 kW frequency of 13.56 MHz is applied to the coil 156 and themagnets 182 create a magnetic field of about 2000 Gauss.

By locating the source of fluorine ions externally of the semiconductorprocessing chamber 114, allows for introduction of the fluorine ionplasma at more accurately selected locations within the semiconductorprocessing chamber 114. The fluorine ion plasma may also be introducedinto the semiconductor processing chamber 114 in a pre-set manner, suchas by spraying the fluorine ion plasma into the semiconductor processingchamber 114.

Although the description has been directed mainly at the use of a radiofrequency generator for dissociating a gas, it should be understood thatthe invention is not limited to such dissociation of a gas. Othermethods of dissociating a gas may also be used, including dissociationby means of a device emanating microwave frequency.

FIGS. 8,9 and 10 illustrate a plasma generator 212 in another embodimentof the present invention. The plasma generator 212 includes a housing230, generation chamber 232, a radio frequency generator 234 and amagnetic device 236 mounted within the housing 230. The radio frequencygenerator 234 is used to generate a reactive ion plasma within thegeneration chamber 232 and the magnetic device 236 is used to controlthe reactive ion plasma within the generation chamber 232. A gas inlet242 is provided at a first end of the generation chamber 232 and anopposing second end of the generation chamber 232 includes an openingwith a much larger outlet 244. The plasma generator housing 230 iselectrically coupled to a ground 238.

The radio frequency generator 234 includes a bracket 250, a connector252, a radio frequency source 254, and a coil 256. Coil 256 includes twospiral sections 257a and 257b and is coupled to bracket 250 by bracket253. Coil 256 is generally of a tubular construction and is typicallymade of copper with an external silver plating.

The bracket 250 and the connector 252 are located on opposing sides of awall of the housing 230 and a link 258 electrically connects the bracketto the connector 252. Bracket 250 is electrically isolated from housing230. The radio frequency source 254 is connected to the connector 252 sothat alternating current within the radio frequency range is supplied tothe bracket 250.

Coil 256 is generally electrically coupled to bracket 250 at a midpointbetween the two spiral sections 257a and 257b. Coil section 257a spiralsaround the generation chamber 232 between a middle section 352 and aninlet section 350 of chamber 232. Coil 257b, on the other hand, spiralsaround the generation chamber 232 between the middle section 352 and anoutlet section 354 of the chamber. A first end 262a of coil 256 ismounted to a wall of the housing 230 by means of a bracket 264a. Asecond end 262b of coil 256 is also mounted to a wall of the housing 230by means of a bracket 264b. Brackets 264a and 264b are grounded, therebyeliminating the need for a cooling water loop as was described inconnection with the embodiment of FIG. 2. The brackets 253,241,264a and264b support the coil 256 substantially concentrically around thegeneration chamber 232. Alternating current can thus be supplied to coil256, and thus, spiral sections 257a and 257b, by operation of the radiofrequency source 254.

Each of coil sections 257a and 257b typically has about five to tenturns. It is appreciated, however, that the invention is not limited toany specific number of coil turns. The number of turns will generallyincrease with the dimensions of the generation chamber 232 in order toensure sufficient coverage around the generation chamber. In addition,coil sections 257a and 257b are configured such that the magnetic fieldsgenerated by each of the sections are synchronized. That is, the coilsare wrapped around the chamber 232 in the same direction. As a result,the magnetic fields generated by each of the coil sections 257a and 257bare added together in the region between the two coil sections. Byeffectively doubling the magnetic force between coil sections 357a and357b, the ionization of the gas within the middle section 352 of chamber232 is greatly enhanced.

The split coil configuration, as shown in FIG. 9, also results in a moreuniform electric field across the length of coil 256, as opposed to acoil having a single spiral section that extends along the full lengthof the chamber 232. In a plasma generator having a coil with a singlespiral section, the electric field is concentrated within the first fewloops of the coil which are located near the inlet section 350 of thechamber 232.. As such, the heat generated within the inlet section ofthe chamber much higher than the other chamber sections. By providing acoil 256 having two spiral sections 257a and 257b, the power into thechamber 232 is more evenly distributed, resulting in a more efficientionization process and better temperature control.

Splitting the radio frequency current between the coil sections 257a and257b also results in a net voltage drop across the coil 256 and a highercurrent flow for a given power input. The higher current enhances themagnetic field that is produced by each of coil sections 257a and 257bwhich increases the efficiency of the system. Moreover, the voltage dropreduces the possibility of capacitance coupling between the plasmawithin chamber 232 and the coil 256, thereby making the plasmageneration system more robust and efficient.

As previously discussed, each of coil sections 257a and 257b is coupledto a grounded bracket 262a and 262b, respectively. By grounding therespective ends of the coils sections, the likelihood of producingsecondary plasma within the inlet section 350 and outlet sections 354 ofchamber 232 is greatly reduced since there is little, or no, electricfield within these sections of the chamber to induce ionization of thegas. In addition, since there is essentially no voltage potentialbetween the end coils of spiral sections 257a and 257b and the adjacentplasma generator components located at the gas inlet 242 and plasmaoutlet 244 of the chamber 232, the possibility of capacitance couplingoccurring within sections 350 and 354 is greatly reduced. The likelihoodthat sputtering will occur within sections 350 and 354 is also reduced.

Capacitors 266 bridge the bracket 250 and a wall of the housing 230. Thecapacitors 266 are selected to match the frequency supplied by the radiofrequency source with the conductance characteristics of the coil 256 sothat the alternating power delivered to the coils is tuned for optimalreasons.

A water inlet connector 268 and a water outlet connector 270 extendthrough a wall of the housing 230. The water inlet and outlet connectorsare located outside housing 230 and are supported by brackets 269 and271, respectively. Water inlet connector 268 is coupled to the first end262a of coil 256, whereas the water outlet connector 270 is coupled tothe second end 262b of the coil. Water 274 can thus be introduced intothe water inlet connector 268, whereafter the water flows through coil256 and out of the water outlet connector 270. The temperature of thecoil 256 is therefore controlled by the flow of water through tubularportion of coil 256. By controlling the temperature of coil 256,variations in the electrical characteristics (e.g., inductance,resistance, etc.) of the coil 256 are minimized permitting a bettercontrol of the ionization process.

The magnetic device 236 is in the form of tubular member 280 locatedaround the coil 256. In one embodiment, tubular member 280 has fourpermanent magnets 282 attached to an inner surface thereof. The magnets282 extend along the length of the tubular member 280. The tubularmember 280 is made of a magnetically conductive material to provide aclosed loop path for the magnetic fields generated by magnets 282. Themagnetic device 236 is configured such that the ions produced within thechamber 232 are confined within a central region of the chamber, awayfrom the internal wall of the chamber. In one such embodiment, magnets282 oppose one another with the generation chamber 232 located betweenthe magnets 282. The magnets create a magnetic field of between 200 and4000 Gauss, typically about 2000 Gauss. The magnetic field created bythe magnets may adjusted to meet the performance requirements of aparticular application.

Turning now to FIG. 10, a partial cross-sectional top view of plasmagenerator 212 is shown. A gas inlet assembly 241 is provided fordirecting and disbursing a gas into the inlet section 350 of chamber232. The gas inlet assembly 241 includes a gas inlet adapter 220 and asleeve 222. As shown in FIG. 11, inlet adapter 220 includes a flangesection 230, a protruding cylindrical portion 231 and a gas inlet 242that is connectable to a gas source (not shown). A plurality ofdistribution holes 226 are provided within the gas inlet passage todistribute a gas around the periphery of cylindrical portion 231.Pursuant to one embodiment of the invention, the inlet adapter has aninlet diameter of 0.188 inches and contains four distribution holes 226,each of the holes having a diameter of 0.098 inches. A recess 228 alongthe periphery of cylindrical portion 231 produces an annular gap betweenthe inlet adapter 220 and sleeve 222 when the components are assembledwithin the plasma generator 212. The annular gap has a thickness ofabout 0.065 inches. By introducing the gas into the chamber 232 throughthe annular gap, the gas is more evenly distributed into the inletsection 350 of the chamber. The gas inlet assembly configuration alsoprohibits the cool gas from entering the chamber 232 and impingedirectly on the internal wall of the chamber 232, thereby minimizingthermal stresses in the chamber wall. The use of a thin profile annularpassage for directing a gas into the chamber also reduces the likelihoodthat an ion will be introduced into the passage. The introduction ofions into the inlet passage could cause sputtering to occur within thepassage, thus resulting in the generation of unwantedparticles/contaminates.

It is important to control the temperature of the various plasmagenerator components to within certain prescribed limits. For example,it is important to control the temperature of the magnets 282 since themagnets will begin to demagnetize when they reach a certain thresholdtemperature. O-rings in the system must also be maintained below acertain temperature, otherwise the o-ring coating (e.g., Teflon) willmelt. In addition, some form of temperature control is necessary tomaintain temperature gradients within the sapphire chamber 232 to withinacceptable limits.

In accordance with one embodiment of the present invention, a coolingjacket or casing 276 is provided around generation chamber 232. Thecasing 276 is sized such that a cooling medium channel 278 is disposedbetween the inner wall of casing 276 and the external wall of chamber232. A cooling medium inlet connection 272 is provided at one end of thegeneration chamber, while a cooling medium outlet connection 274 isprovided at the opposing end of the chamber. Cooling of the chamber 232is achieved by directing a cooling medium into connector 272, throughcooling channel 278, and out connection 274. The cooling mediumpreferably comprises compressed air, but may include other types ofcooling mediums. Compressed air is a preferred cooling medium since iteasily accommodates the attachment of a conventional leak detectiondevice at the outlet connection 274. Additionally, if a leak existswithin chamber 232, the introduction of air into the system will notcause damage to the plasma generator or the semiconductor processingchamber.

The plasma generator 212, as depicted in FIGS. 8 through 10, isconfigured to accommodate compressed air as the cooling medium.Compressed air causes a high density of air molecules to flow throughcooling channel 278 and also induces turbulent flow through coolingchannel. Each of these factors contribute to enhancing the efficiency ofthe cooling system. Connections 272 and 274 are coupled to channel 278through an inlet manifold 280 and an outlet manifold 282, respectively.In one embodiment, the air flow channel 278 has a thickness ofapproximately 0.04 inches and a length of approximately 10 inches.

FIG. 12 is an enlarged view of inlet manifold 280. Outlet manifold 282typically has the same configuration as the inlet manifold 280 to ensurethat the air flow is even throughout the length of the cooling channel278. The inlet and outlet manifolds 280 and 282 are placed near theplasma generator o-rings 320 through 325 to provide cooling to theo-rings.

Inlet manifold 280 includes an inlet port 290 in which the air inlettubing 291 is attached. The inlet port 290 is coupled to an annulardistribution ring 294 that contains a plurality of spaced apartapertures 296. Compressed air enters the inlet port 290 of manifold 280and is evenly distributed into the cooling channel 278 through theapertures 296 in the distribution ring 294. In one embodiment, inlettubing 291 comprises 1/4 inch tubing having an inside diameter of 0.219inches with the distribution ring 294 containing eight apertures 296,each aperture having a diameter of 0.109 inches. The combined area ofapertures 296 is significantly greater than the inside area of tubing291. This ensures that the air flow is not restricted after it has beenintroduced into the inlet connection 272. The expanding flow volumewithin inlet manifold 280 also creates a cooling effect due to theexpansion of the compressed air flowing into the inlet manifold. Inorder to induce a cooling of the compressed area, it is desirable toprovide a relatively large volume expansion ratio between the coolingmedium inlet tubing 291 and the inlet manifold 280. For example, in oneembodiment, the volume expansion ratio within the inlet manifold isapproximately 1/10.

It is important to note that the present invention is not limited by themanner in which the plasma generator is cooled. For instance, in lieu ofusing compressed air as the cooling medium, an inert gas, or othercooling medium, such as deionized water may be used. Other forms ofcooling, such as water coils, may be used in lieu of the cooling jacketdescribed above.

Note also that the water and air connections 268, 270, 272 and 274 arelocated external to the plasma generator housing 230. Therefore, anyleakage at these connections will not result in the discharge of air orwater into the interior of the housing.

An ionization detection assembly 310 is attached to the outside ofhousing 230 by a bracket 311. An opening 312 in housing 230 is providedfor accommodating a connector that couples assembly 310 to an ionizationdetector 314. The split configuration of coil 256 permits the ionizationdetector 314 to be placed at the middle section 352 of chamber 232 wherethe majority of the ionization occurs, thus providing an accurateindication of the ionization process.

The foregoing description has been directed primarily at a system whichincludes a semiconductor processing chamber which is made of aluminum,and which is cleaned with a reactive fluorine ion plasma. Othersemiconductor processing chambers may exist or may in the future bedesigned which are made of materials which are attacked by fluorineions. Other reactive ion plasmas would thus be utilized in order toclean these other semiconductor processing chambers. Quartz is anexample of a material which is attacked by fluorine ions. A chlorinecontaining gas, such as Cl₂, may, for example, be utilized for asemiconductor processing chamber which is made of quartz. Cl₂dissociates into Cl⁻ ions which would be suitable for purposes ofcleaning a quartz containing semiconductor processing chamber. Cl⁻ isalso aluminum and stainless steel "friendly" so that the processingchamber may be made partially of quartz and partially of stainless steelor aluminum.

Although the foregoing description has been directed primarily atcleaning of a semiconductor processing chamber, it should be understoodthat other equipment, such as interconnecting pipes, may also be cleanedin a similar manner.

What is claimed is:
 1. An apparatus comprising:a chamber having an inletopening at a first end, an outlet opening at a second end, an internalsurface and an external surface; and an electrically conductive coildisposed around at least a portion of the external surface of thechamber connectable to an alternating current source; and a magnet meanscreating a magnetic field confining the ions to an area within thechamber, the area being away from the internal wall.
 2. The apparatus ofclaim 1 wherein the coil emanates a frequency which dissociates a gas,when contained within the chamber, into reactive ions.
 3. The apparatusof claim 2 wherein the frequency is within the radio frequency range. 4.The apparatus of claim 1 wherein the generation chamber is tubular. 5.The apparatus of claim 1 wherein the coil includes a fluid passagepassing through at least a portion of the length thereof.
 6. Theapparatus of claim 1 wherein the magnet means includes a first set ofmagnets on opposite sides of the area and a second set of magnets onopposite sides of the area.
 7. The apparatus of claim 6 wherein thefirst set of magnets and the second set of magnets have oppositepolarity.
 8. The apparatus of claim 1 wherein the magnet means islocated externally of the generation chamber.
 9. The apparatus of claim1 wherein the coil generates a vibration within the chamber within theradio frequency range.
 10. The apparatus of claim 1 further comprisingmeans for directing a cooling medium across the external surface of thechamber.
 11. The apparatus of claim 10 wherein the cooling mediumcomprises compressed air.
 12. The apparatus of claim 1 wherein thedirecting means includes a casing surrounding at least a portion of theexternal surface of the chamber, the casing and external wall of thechamber producing a flow channel.
 13. The apparatus of claim 1 furthercomprising a semiconductor processing chamber and a conduit providing apassage between the outlet opening and the semiconductor processingchamber.
 14. An apparatus comprising:a chamber having an internalsurface and an external surface; an inlet into the chamber; means fordissociating a gas, when contained within the chamber, into reactiveions; magnet means creating a magnetic field confining the ions to anarea within the chamber; a semiconductor processing chamber; and aconduit allowing the flow of ions from the chamber to the semiconductorprocessing chamber.
 15. The apparatus of claim 14 wherein the magnetmeans confines the ions to an area away from the internal wall of thechamber.
 16. The apparatus of claim 14 wherein the generation chamber istubular.
 17. The apparatus of claim 14 wherein the dissociation meansincludes a member emanating a frequency which dissociates the gas intoreactive ions.
 18. The apparatus of claim 17 wherein the frequency iswithin the radio frequency range.
 19. The apparatus of claim 17 whereinthe member is located externally of the generation chamber.
 20. Theapparatus of claim 17 wherein the member spirals around the generationchamber.
 21. The apparatus of claim 17 wherein the member is an elongatemember with a fluid passage passing through the length thereof.
 22. Theapparatus of claim 14 wherein the magnet means includes at least a firstset of magnets on opposite sides of the area and a second set of magnetson opposite sides of the area.
 23. The apparatus of claim 22 wherein thefirst set of magnets and the second set of magnets have oppositepolarity.
 24. The apparatus of claim 14 wherein the magnet means islocated externally of the generation chamber.
 25. The apparatus of claim24 wherein the directing means includes a casing surrounding at least aportion of the external surface of the chamber, the casing and externalwall of the chamber producing a flow channel.
 26. The apparatus of claim14 further comprising means for directing a cooling medium across theexternal surface of the chamber.
 27. An apparatus comprising:ageneration chamber having an internal wall; means for dissociating agas, when contained within the chamber, into reactive ions; and magnetmeans creating a magnetic field confining the ions to an area within thechamber.
 28. The apparatus of claim 27 wherein the magnet means includesat least a first set of magnets on opposite sides of the area and asecond set of magnets on opposite sides of the area.
 29. The apparatusof claim 28 wherein the first set of magnets and the second set ofmagnets have opposite polarity.
 30. The apparatus of claim 27 whereinthe magnet means is located externally of the generation chamber. 31.The apparatus of claim 27 wherein the dissociation means includes amember emanating a frequency which dissociates the gas into reactiveions.
 32. The apparatus of claim 31 wherein the frequency is within theradio frequency range.
 33. The apparatus of claim 27 wherein the memberis located externally of the generation chamber.
 34. The apparatus ofclaim 33 wherein the member spirals around the generation chamber. 35.The apparatus of claim 27 wherein the dissociation means includes anelectrically conductive coil disposed around at least a portion of thechamber, the coil producing an electric field and magnetic field whenconnected to an alternating current source.
 36. The apparatus of claim35 wherein the coil includes a fluid passage through at least a portionof the length of the coil.
 37. The apparatus of claim 27 wherein thechamber includes an inlet opening at a first end, an outlet opening at asecond end, and a central portion located between the first and secondends, the dissociation means including a first electrically conductivecoil disposed between the central portion and the first end of thechamber and a second electrically conductive coil disposed between thecentral portion and the second end of the chamber, each of the first andsecond coils producing an electric field and magnetic field whenconnected to an alternating current source.
 38. The apparatus of claim37 wherein each of the first and second coils includes a fluid passagethrough at least a portion of the length of the coil.
 39. The apparatusof claim 27 wherein the magnet means is configured to confine thereactive ions to an area away from the internal wall of the chamber. 40.A method of cleaning a semiconductor processing chamber, comprising thesteps of:dissociating a gas into reactive ions; magnetically confiningthe ions; and introducing the ions into the semiconductor processingchamber.
 41. The method of claim 40 wherein the gas is dissociated by afrequency within the radio frequency range.
 42. The method of claim 40wherein the gas is dissociated within a generation chamber which is madeof a material which is resistant to the ions.
 43. The method of claim 42wherein the ions include fluorine.
 44. The method of claim 43 whereinthe generation chamber is made out of sapphire.
 45. The method of claim40 wherein the ions include fluorine.
 46. The method of claim 40 whereinthe ions are introduced into the semiconductor processing chamber at twoor more different locations.
 47. The method of claim 40 wherein the ionsare sprayed into the semiconductor processing chamber.
 48. A method ofcleaning a semiconductor processing chamber, comprising the stepsof:introducing a gas into a generation chamber; means for dissociatingthe gas into reactive ions; magnetically confining the ions to an areawithin the generation chamber; and introducing the ions to thesemiconductor processing chamber.
 49. The method of claim 48 wherein thegas is dissociated at a frequency within the radio frequency range. 50.A method of generating a plasma, comprising the steps of:dissociating agas into reactive ions; and magnetically confining the ions.
 51. Themethod of claim 50 wherein the ions are magnetically confined while theyare being formed.
 52. The method of claim 50 wherein the gas isdissociated and the ions are magnetically confined while the gas flowsinto a chamber and while the ions are flowing out of the chamber.